This invention pertains to primer compositions which form a strong transparent film on a base material (or substrate) by normal air drying.
The technique of treating base materials with various primers before applying room-temperature cured silicone rubber as an adhesive is a general and widely used adhesion method involving base materials and silicone rubber cured at room temperature. One of the main uses of this silicone rubber cured at room temperature is for sealing buildings. However adhesion involving mortar, autoclaved light-weight concrete (ALC) and pre-cast concrete (PC) is always difficult and displays problems in durability. Since these base materials are porous, the applied primer permeates inward and makes it difficult to form a strong film on the adhesion side. Also the free passage of water through capillary tubes lessens their bonding strength. Furthermore, the basic strength of these materials encourages deterioration of primer compositions and causes delamination. The use in recent years of aluminum (anti-corrosive aluminum, natural color-forming aluminum), metals such as stainless steel, special coating materials, plastics, and organic rubbers as building materials has necessitated the development of compositions which form a strong film on these base materials. Inventions using silane or siloxane containing mercapto groups have been introduced (Public issue No. 139831 of TOKKAI, 1976), but these also are ineffective when the base materials are vinylchloride resin, acrylic resin, polysulfide type sealing material or concrete. This present invention corrects these past deficiencies by presenting compositions which form films that are heat-resistant, water-resistant, and alkali-resistant, and will form strong films on mortar, concrete, ALC, PC polyvinylchloride, aluminum, metals such as stainless steel, special painted surfaces, plastics, and organic rubber.